skip to content

The Virtual Engine Sound – For Your Safety


Eco-friendly cars that use silent motors started to make an artificial sound for the safety of pedestrians walking around them. Here's the new virtual engine sound system developed by Hyundai Mobis.

People walking on the streets, especially around the small alleyways, feel harder to sense the green cars, including hybrid vehicles, because those vehicles don’t use combustion engines which normally make loud noises. This is why automakers felt the need to make the motors noisy again.

Automakers began to use the Virtual Engine Sound System (VESS) to solve such a problem. They put a speaker under the bonnet to produce an artificial sound that alerts people when the car is moving. And Hyundai Mobis recently announced its brand-new VESS.

VESS to keep people safe

For safety, VESS is usually mandatory around the world.

According to United Nations Economic Commission for Europe (UNECE), the World Forum for Harmonization of Vehicle Regulations (WP.29) has adopted a new Regulation on Quiet Road Transport Vehicles (QRTV) which aims to minimize the risk posed by silent cars. According to the new Regulation, quiet cars should be equipped with a VESS to create artificial noise.

South Korean government also set a regulation so that any vehicle driving slower than 30 km/h must make an alert sound under 75dB, and even let the pedestrians know when the driver speeds up through different sound. Though details might vary depending on countries, the VESS itself is definitely trending around the world.

The old version of VESS had its downside.

An ordinary VESS has a speaker producing an artificial engine sound inside the engine room, but the sound was blocked and bounced off the bonnet. The system also could not eliminate the sound resonance created at a certain frequency, hence making a totally different sound from what the manufacturer intended in the first place.

The old VESS sometimes even needed additional speakers or other compartments to deliver an alert sound loud enough to reach pedestrians. It was not space-efficient indeed.

Grille as a vibrating plate

The new VESS uses the grille as the speaker of the system.

Hyundai Mobis has developed a new virtual engine sound system using grille covers. The grille was used as a vibrating plate to overcome its predecessor’s weaknesses, improving the performance. The company said the technology has been in development since 2018, while two related patents have also been registered.

The sound system not only emits the engine sound but also a beeping sound when the traffic indication lamp or the charging system is activated. The company said the virtual engine sound system can also be used as a speaker for music, a useful feature for outdoor activities like camping.

The new VESS system is based on a simple yet durable design and structure.

Hyundai Mobis said its new system attached the actuator to the back of the front grille cover and used the grille itself as a vibrating plate, unlike the previous design that used an ordinary speaker consisting of a vibrating board to propagate the sound to the outside.

The grille cover directly delivers the sound, maintaining the sound intensity. The system also houses a waterproof seal for enhanced durability. Hybrid vehicle owners can put the actuator inside the bumper to utilize the bumper as a vibrating plate.

The actuator became smaller and lighter.

Hyundai Mobis explained the company significantly enhanced the design of the actuator for better performance. The new system reduced the weight to one-third of existing products and the size to half, especially for smaller vehicles. They also eliminated the bracket or housing because they no longer needed to fasten the speaker some place else.

Hyundai Mobis expects that the autonomous vehicles in the future would also use their new VESS.

To meet a number of environmental regulations all around the world, green cars will keep evolving, and so will the related technologies such as VESS. The company also expects that there will be more demand and interest among car manufacturers about enabling active communication from inside to outside the car.